Cross institutional collaboration in assessment: a case on progress testing.

The practice of assessment is governed by an interesting paradox. On the one hand good assessment requires substantial resources which may exceed the capacity of a single institution and we have reason to doubt the quality of our in-house examinations. On the other hand, our parsimonity with regard to our resources makes us reluctant to pool efforts and share our test material. This paper reports on an initiative to share test material across different medical schools. Three medical schools in The Netherlands have successfully set up a partnership for a specific testing method: progress testing. At present, these three schools collaboratively produce high-quality test items. The jointly produced progress tests are administered concurrently by these three schools and one other school, which buys the test. The steps taken in establishing this partnership are described and results are presented to illustrate the unique sort of information that is obtained by cross-institutional assessment. In addition, plans to improve test content and procedure and to expand the partnership are outlined. Eventually, the collaboration may even extend to other test formats. This article is intended to give evidence of the feasibility and exciting potential of between school collaboration in test development and test administration. Our experiences have demonstrated that such collaboration has excellent potential to combine economic benefit with educational advantages, which exceed what is achievable by individual schools.

Performance of phenotypic and genotypic methods to determine the clinical relevance of serial blood isolates of staphylococcus epidermidis in patients with septicemia.

Five typing methods, including biotyping (API ID32; BioMérieux, Marcy l'Etoile, France), quantitative antibiogram typing based on actual zone sizes, plasmid typing, randomly amplified polymorphic DNA (RAPD) analysis (with primer M13 and primer set ERIC-2-1026), and pulsed-field gel electrophoresis (PFGE), were compared with a previously performed method of DNA fingerprinting by AFLP (amplified fragment length polymorphism analysis) for their performance in the typing of blood isolates of Staphylococcus epidermidis. Sixteen epidemiologically unrelated strains and 11 sets of four blood culture isolates from 11 patients with septicemia were used. The stabilities and reproducibilities of the patterns, the discriminatory capacities of the methods, and the ability to apply the methods to blood culture isolates were used as performance criteria. All strains tested were typeable by each method, and the patterns were stable and reproducible. The numbers of different types within the collection of 16 epidemiologically different isolates were 5 by biotyping, 14 by antibiogram typing, 4 by plasmid typing, 9 by the RAPD assay (combination of results with primer M13 and primer set ERIC-2-1026), and 16 by PFGE. Within the 11 sets of four blood culture isolates the types found by quantitative antibiogram typing, plasmid typing, and PFGE were unique for each set, whereas by biotyping and RAPD analysis some types were observed in more than one set. The results of biotyping did not correspond with the results of the other methods or the results of AFLP. For 6 of the 11 sets, the results of all methods except those of biotyping corresponded completely. Quantitative antibiogram typing, PFGE, and AFLP proved to be the most accurate of the six typing methods tested.

Acinetobacter junii causes life-threatening sepsis in preterm infants.

Acinetobacter junii caused sepsis in six preterm infants in our neonatal unit within 48 h. Each infant with clinical signs of systemic infection and activation of the acute phase response had two positive blood cultures with Acinetobacter junii. The sudden onset, the short duration of the outbreak and the fact that none of the infants were colonized by A. junii suggested a common source of A. junii administered directly into the blood. The only feature shared by all six affected newborns was an intravenous fat emulsion (Intralipid 10%), which was shown to be an excellent growth medium for A. junii. Sepsis did not occur in four infants with 20% fat emulsion or amino acids only. Vaminolact did not support growth of the outbreak strain. The immediate source of the outbreak could not be identified: samples of the actual feeds given were not available for investigation, but A. junii was not isolated from parenteral solutions with identical batch numbers used in the septic infants. We conclude that Acinetobacter junii can cause a life-threatening infection in preterm neonates. Contaminated intravenous fat emulsion is implicated as a possible source of the infection. As a part of rigid infection control, intravenous feedings should be prepared under aseptic conditions.

Methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii: an unexpected difference in epidemiologic behavior.

BACKGROUND: The Dutch guideline on hospital policy for the prevention of nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA) states that patients transferred from hospitals abroad must be placed in strict isolation immediately on admission to a hospital in the Netherlands. Three patients colonized with both MRSA and a multiresistant Acinetobacter were transferred from hospitals in Mediterranean countries to 3 different hospitals in the Netherlands. Despite isolation precautions, Acinetobacter spread in 2 of the 3 hospitals, whereas nosocomial spread of MRSA did not occur. METHODS: For outbreak analysis, the Acinetobacter isolates, identified as Acinetobacter baumannii by the use of amplified ribosomal DNA restriction analysis, were comparatively typed by 4 methods. Comparison of isolation measures in the hospitals was performed retrospectively. RESULTS: In the 2 hospitals in which nosocomial spread of Acinetobacter occurred, most of the epidemiologically related isolates were indistinguishable from the index strains. In these 2 hospitals, isolation measures were in concordance with those recommended for the prevention of contact transmission. The precautions of the hospital in which no outbreak occurred included the prevention of airborne transmission. CONCLUSIONS: Precautions recommended for multiresistant gram-negative organisms are insufficient for the prevention of nosocomial spread of multiresistant Acinetobacter. The airborne mode of spread of acinetobacters should be taken into account, and guidelines should be revised accordingly.

Effectiveness of resins in neutralizing antibiotic activities in bactec plus Aerobic/F culture medium.

Incorporating resins in blood culture media can effectively reduce the activities of several antibiotics. It was shown that the activities of some generally used antibiotics decreased by 80 to 90% within 2 h in Bactec Plus Aerobic/F resin-containing culture medium. Bactec vials containing resins were still found to be positive for bacteria when antibiotics were present. The addition of beta-lactamase shortened the detection time irrespective of the presence of resins.

AFLP typing of Staphylococcus epidermidis in multiple sequential blood cultures.

AFLP is a novel high-resolution PCR-based DNA fingerprinting method generating complex banding patterns that can be used for comparative analysis. In the present study, the applicability of AFLP in fingerprinting Staphylococcus epidermidis isolates was investigated. The criteria considered were stability of patterns, reproducibility, discriminatory capacity and consistency with epidemiological context. Repeated testing of strains and investigation of subcultures showed that AFLP patterns were reproducible and stable with an intrastrain similarity of S > or = 94% as determined by analysis of digitized patterns. Fifteen unrelated strains were heterogeneous, with a level ranging from 78-93%. The applicability of AFLP in epidemiological studies of S. epidermidis was tested on 11 sets of four blood isolates each, from 11 patients with suspected septicaemia. Nine sets had indistinguishable or highly similar AFLP patterns for each isolate per set, while two sets had heterogeneous patterns. These results show that AFLP has high discriminatory power for strain identification in S. epidermidis.

Identification of multiresistant Staphylococcus epidermidis in neonates of a secondary care hospital using pulsed field gel electrophoresis and quantitative antibiogram typing.

AIMS: To determine the diversity of types of Staphylococcus epidermidis in a neonatal care unit of a secondary care hospital in the Netherlands. METHODS: In a prospective study, specimens from nose, ear, axilla, umbilicus, and groin were taken from patients twice a week during a period of up to two weeks. All isolates were typed by both pulsed field gel electrophoresis (PFGE) and antibiogram analysis. RESULTS: Fifty three S epidermidis isolates from 15 of 24 patients were obtained in one to four surveys. Fourteen isolates from six patients had a common PFGE pattern and were of one multiresistant antibiogram type. The remaining 39 isolates were allocated to 24 sporadic PFGE types and were more susceptible to antibiotics. Colonisation with the multiresistant strain correlated with a long period of stay and with the use of specific antibiotics. The multiresistant isolates were related closely to isolates of S epidermidis found in a recent study in a teaching hospital in the vicinity of the secondary care hospital. CONCLUSION: Repeated sampling and the use of two typing methods allowed the identification of two closely related multiresistant S epidermidis strains in two hospitals in the same area.

Changing susceptibilities of coagulase-negative staphylococci to teicoplanin in a teaching hospital.

The susceptibility of two collections of coagulase-negative staphylococci (CNS) isolated from clinical specimens for teicoplanin and vancomycin were compared. They comprised 91 and 101 isolates, collected in 1985 and 1994 respectively, from different departments of a teaching hospital. MICs of vancomycin and teicoplanin were determined by a modified Etest method. Additionally, a disc diffusion test was performed for teicoplanin. All isolates were susceptible to vancomycin (MIC < or = 4 mg/L). Two of the 91 isolates collected in 1985 were intermediate to teicoplanin (MIC between 8 and 32 mg/L), whereas in 1994 the number of intermediate isolates was 20 out of 101 (P < 0.01). The correlation between MICs, as determined by the modified Etest assay, and disc diffusion zones was poor (r = -0.35). Results show that resistance to teicoplanin in CNS has increased in the study hospital over a period of 9 years. This increase is likely to be correlated with the introduction of teicoplanin. Furthermore, a disc diffusion method does not appear to be the first method of choice for detection of strains of CNS with diminished susceptibility to teicoplanin.

Serratia marcescens infections in neonatal departments: description of an outbreak and review of the literature.

An outbreak of colonization and infection with Serratia marcescens occurred in a neonatal intensive care unit (NICU). S. marcescens was isolated from five preterm infants (gestational age 25-30 weeks). Two infants developed septicaemia, which were both fatal, and one infant (the presumed index case) had conjunctivitis due to S. marcescens. Two infants were colonized without clinical signs of infection. All infants were treated with antibiotic regimens including ciprofloxacin and gentamicin. The DNA fingerprints of isolates were determined by enterobacterial repetitive intergenic consensus primers by the polymerase chain reaction. This showed that a single strain had spread in the NICU. An extensive investigation pointed to an infant born from a mother with an intra-uterine infection after prolonged rupture of foetal membranes as a presumed source of the outbreak. A reservoir, other than the infected or colonized infants and their immediate vicinity, was not found, with the sole exception of the waste jar of a Na+/ K(+)-analysis apparatus. Containment of the outbreak was achieved by closure of the NICU for new admissions, strict hygienic measures and cohort nursing of the infected and colonized infants. It was considered especially important to handle the infants with gloves, since frequent hand carriage of staff with S. marcescens was found when gloves were not used.

Outbreak of septicaemia in neonates caused by Acinetobacter junii investigated by amplified ribosomal DNA restriction analysis (ARDRA) and four typing methods.

Septicaemia caused by Acinetobacter occurred in six infants in the neonatal unit. A total of 18 acinetobacters were isolated from blood cultures, cultures of intravascular catheters, and surveillance cultures. Twelve isolates from the six affected infants were identified as Acinetobacter junii by the use of a novel method, amplified ribosomal DNA restriction analysis (ARDRA). Typing of the organisms using the biochemical profiles of the API 20NE system, antibiogram typing, cell envelope protein electrophoresis, and PCR fingerprinting with two primer sets, ERIC1/ERIC2 and ERIC2/ 1026, showed that these 12 isolates were indistinguishable, whereas the remaining six isolates were different. The six infants recovered after therapy with ciprofloxacin alone in five cases and with a combination of ciprofloxacin and gentamicin in one case. This study showed that A. junii is capable of causing a serious, though non-fatal infection in neonates. The combined use of genotypic and phenotypic methods allowed the rapid separation of epidemic from non-epidemic isolates. It is concluded that for a better understanding of the role of the various Acinetobacter genomic species in human pathology, identification of acinetobacters according to the recent taxonomy is imperative.

Guidelines for detection of penicillin tolerance in Streptococcus pyogenes by MIC-MBC method.

Disagreement on a uniform and accepted method of testing penicillin tolerance in Streptococcus pyogenes prevents a meaningful comparison of results of various studies on tolerance and an assessment of the contribution of this phenomenon to treatment failure. Therefore guidelines are needed.

Evaluation of the ability of a commercial system to identify Acinetobacter genomic species.

A collection of 130 Acinetobacter strains identified by DNA hybridization to 18 different genomic species was used to assess the ability of the API 20NE system (bioMérieux, France) to identify Acinetobacter genomic species and to determine its accuracy. Fifty-eight (87%) of the 67 strains of genomic species defined in the database (version 5.1) were identified to the appropriate genomic species. The Acinetobacter baumannii strains and the Acinetobacter haemolyticus strains were all identified correctly. Three of five Acinetobacter junii strains, three of eight Acinetobacter johnsonii strains, and 11 of 13 Acinetobacter lwoffii strains were also identified correctly. The 58 correctly identified strains represented 45% of the total 130 strains. Thirty-six of the 72 inappropriately identified strains were designated Acinetobacter baumannii. Thirty-one of these 36 strains belonged to genomic species 1 (Acinetobacter calcoaceticus), 3, or 13TU. Analysis of the profiles showed that the API system does not discriminate between genomic species 1, 2, 3, and 13TU. Lumping of these groups into the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in the API 20NE database would make the system considerably more accurate. Incorporation of these data into the database may improve identification of the remaining genomic species, including some that are not defined. However, the discriminative power of the tests in the API galleries is insufficient for correct identification of all Acinetobacter genomic species.

Penicillin tolerance and treatment failure in group A streptococcal pharyngotonsillitis.

Failure of treatment of group A streptococcal pharyngitis and tonsillitis is well documented. One of the possible explanations for treatment failure is penicillin tolerance in group A streptococci. Reports on the prevalence of penicillin tolerance among group A streptococci (0-100%) and the presumed relationship with therapeutic failure vary considerably. Therefore, it appears worthwhile to review pharyngotonsillitis studies, devoting special attention to the variables of MIC-MBC laboratory determinations such as inoculum preparation, composition and volume of test medium, and the criteria used to define penicillin tolerance. Alternative methods (gradient-replica plate method, beta-lactamase disk test, time-kill assay, and cell-lysis assay) are discussed. It is concluded that technical factors and the definitions used influenced the reported rates of penicillin tolerance. The epidemiological data suggest that tolerance is not limited to a single streptococcal serotype. Furthermore, there is not sufficient data to support a correlation between in vitro penicillin tolerance of group A streptococci and treatment failure, either in clinical cases or in animal studies. On the other hand, evidence to exclude penicillin tolerance as a cause of treatment failure is also not available. Therefore, at present penicillin tolerance cannot be ruled out as a cause of penicillin treatment failures.

Susceptibility of Streptococcus pyogenes to azithromycin, clarithromycin, erythromycin and roxithromycin in vitro.

The susceptibility of 180 clinical isolates of Streptococcus pyrogenes from six regions of The Netherlands to the macrolide antibiotics azithromycin, clarithromycin, erythromycin and roxithromycin was analysed. The results of a microbroth MIC method, the E-test method and a disk diffusion assay were compared, and the MBC determined. In addition, the susceptibility to erythromycin of 436 clinical isolates of S. pyogenes from the Leiden region was determined. The microbroth MIC90s of azithromycin, clarithromycin, erythromycin and roxithromycin for group A streptococci were < or = 0.5 mg/L. Erythromycin had the lowest MIC90 (0.09 mg/L). The MIC data obtained with the E-test method suggested that clarithromycin and erythromycin had slightly higher anti-streptococcal activity than azithromycin and roxithromycin in vitro. MICs obtained with the E-test were lower than those found with the microbroth method. Only minor discrepancies were observed among the three methods. The MBC50 for both clarithromycin and erythromycin was 0.75 mg/L and 5.0 mg/L for azithromycin and roxithromycin. None of the 180 strains and two of the collection of 436 strains (0.5%) were resistant to erythromycin and the other macrolides tested; MICs ranged from 1 to 16 mg/L. The erythromycin-resistant strains showed an inducible type of macrolide-lincosamide-streptogramin B (MLS) resistance.

Phenotypic characterisation of Acinetobacter strains of 13 DNA-DNA hybridisation groups by means of the biolog system.

A collection of 129 Acinetobacter strains belonging to DNA groups (genomic species) 1-14 (1-7 and 10-12 sensu Bouvet and Grimont; 8 and 13-14 sensu Tjernberg and Ursing) were investigated for their ability to oxidise 95 carbon sources in the Biolog system. The strain groupings obtained by cluster analysis with the Biolog software were compared with the results of DNA-DNA hybridisation studies. Strains of DNA groups 1 (A. calcoaceticus), 2 (A. baumannii), 3 and 13 were linked in one cluster, as were DNA groups 4 (A. haemolyticus) and 6, DNA groups 10 and 11, and DNA groups 8 (A. lwoffii) and 12 (A. radioresistens). Strains of DNA group 5 (A. junii) were grouped in a single cluster with one strain of DNA group 4. Strains of DNA groups 7 (A. johnsonii) and 14 formed separate clusters. With the exception of the linkage of DNA groups 8 and 12, these results correlated with classification of reference strains of the DNA groups by DNA-DNA hybridisation, but six strains of four different DNA groups were not allocated to the clusters of their respective DNA groups. In the case of DNA groups 4, 5, 6, 7, 10, 11 and 14, at least one carbon source oxidation test could be used to differentiate them from the other DNA groups.

Genotypic and phenotypic analysis of Borrelia burgdorferi isolates from The Netherlands.

Sixty-three Borrelia burgdorferi isolates recovered from Ixodes ricinus ticks collected in 17 locations in The Netherlands and three Dutch human skin isolates were characterized by rRNA gene restriction fragment length polymorphism, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western blotting (immunoblotting). All three human isolates belonged to B. burgdorferi group VS461. Of the tick isolates, 29 (46%) were B. burgdorferi sensu stricto, 2 (3%) were group VS461, 19 (30%) were Borrelia garinii, and 13 (21%) were different from any previously described genomic species. On the basis of the criteria described, 12 isolates formed a distinct genomic group, designated M19. rRNA gene restriction patterns of the group M19 isolates resembled but were not identical to the B. garinii patterns. Hybridization of digested DNA with a flagellin probe confirmed the separation of group M19 from the B. garinii isolates. One isolate, M63, was different from all the others. In conclusion, the occurrence of B. burgdorferi sensu stricto, B. garinii, and B. burgdorferi group VS461 in ticks from The Netherlands corresponds with the occurrence of these genomic species among tick isolates from other European countries. However, our findings suggest that B. burgdorferi sensu lato probably contains more than three genomic species.

Evaluation of nine serological tests for diagnosis of Lyme borreliosis.

Two hundred serum specimens including 13 sera from patients with early Lyme borreliosis, 21 patients with late Lyme borreliosis, 15 rheumatoid factor positive sera, 31 sera from patients with syphilis and 84 sera from healthy controls were used to evaluate the following assays for the detection of antibodies to Borrelia burgdorferi: two in-house enzyme immunoassays (EIAs), two in-house immunofluorescent antibody assays (IFAs), a commercial haemagglutination assay (HA) (Diagast) and four commercial EIAs (Diagast, Dako, Diamedix, Whittaker Bioproducts). In early and late Lyme borreliosis sera sensitivity ranged from 8% to 62% and from 62% to 86% respectively. With the exception of the Dako EIA, which was signifcantly more sensitive in early Lyme borreliosis (62%) than the Diagast HA (8%) (p = 0.05), differences in sensitivity were not significant. In healthy controls the specificity was > or = 95% for all tests. Taking into account sensitivity, specificity, intra-test and inter-test precision, ease of performance and cost, the Dako EIA and Diamedix EIA were shown to be good alternatives to the in-house EIA and in-house IFA. Because of its low sensitivity in diagnosis of both early and late Lyme borreliosis, use of the Diagast HA should be discouraged.